Mortar and ammunition



Dec. 11, 1968 a OL Em 3,416,401

' MORTAR AND AMMUNITION Filed ma e, 195s uvmvroxs Bernard J. Golbeck Joseph W. Hunier If E.. v :Y gM auQM/Q' United States Patent 3,416,401 MORTAR AND AMMUNITION Bernard J. Golbeck, Crystal Lake, and Joseph W. Hunter, Chicago, Ill., assignors to the United States of America as represented by the Secretary of the Army Filed May 9, 1956, Ser. No. 583,891 6 Claims. (Cl. 89-1) This invention relates to ordnance devices and more particularly to obtaining spin on a projectile from a smooth-bore mortar.

We have invented a muzzle loading mortar utilizing a rifled cartridge and projectile having distinct advantages in certain applications over either rifled guns or smooth bore mortars utilizing fin stabilized projectiles.

An object of this invention is to provide a muzzle loading mortar with high accuracy.

Other objects are to provide a light weight mortar and a small volume projectile.

Further objects are to provide a mortar with less muzzle flash, less noise and greater range.

Still further objects are to achieve the above in a cheap and simple manner with a device that is sturdy and easy to manufacture.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from the following description and drawings, in which:

FIG. 1 is a plan view, partially broken away, of a mortar constructed according to this invention.

FIG. 2 is a side view of the mortar of FIG. 1 with the tube elevated.

FIG. 3 shows a round of ammunition, partially broken away, for the mortar of FIG. 1.

FIG. 4 shows the cartridge from the round of FIG. 3.

FIG. 5 shows a modified round, partially broken away, for a modified mortar.

FIGS. 1 and 2 show a mortar which may be conventional in every respect except for port 12 and slots 14. It consists of a base plate 16 with two uprights 18 attached thereto. Pivoted to the uprights is trunnion 20 which may be rotated by elevation adjustments which in this case take the form of a worm 22 attached to one upright 18 cooperating with a worm wheel 24 attached to the trunnion 20. Attached to the trunnion between the uprights is a cylindrical tube 26 which is closed at the breech by plug 28. Coaxial with the tube 26 is a firing pin 30 extending into the tube and acting to hold the trunnion 20 to the plug 28 and the tube.

Adjacent the breech of tube 26 is a port 12 in the under side. Also the tube has slots 14 throughout most of its length. The purpose of the port and slots will be explained later. 3

FIGS. 3 and 4 show a round of ammunition for the mortar 10. Projectile 32 has a cylindrical warhead section 34, containing explosive 36, and a tail section 38. Cartridge 40 is cylindrical in shape and fits snugly within a cylindrical bore 42 of the tail section 38. At the closed base 44 of the cartridge 40 is a flange 46. At the open end there is an annular protuberance 48 which mates with any one of a series of increment rings 50 in bore 42. The cartridge is filled with powder 52 for propelling the projectile 32. The powder 52 is hermetically sealed by wad 54 at the open end of the cartridge. There is a percussion cap 56 in the base 44. Pin 58 in the tail section 38 fits in a rifling groove 60, which has a helical angle of about 2",

The first step of operation is to adjust the position of cartridge 40 in bore 42 until protuberance 48 reaches the desired increment ring 50. If maximum range is desired, the round is fired as shown; however, if less range is desired the cartridge is partly withdrawn from bore 42, by pulling on flange 46, so that the powder 52 is less ice efiiciently utilized. The round is then dropped down the muzzle of the mortar 10. The percussion cap 56 strikes the firing pin 30, setting off powder 52. The explosion is contained within the bore 42. The powder utilization is good for mortars despite a short stroke because of the small volume and the snug fit between cartridge 40 and bore 42. The wall of cartridge section 38 withstands the gas pressure; therefore, the mortar tube 26 may be very light weight as it only acts as a guide and not as a container of the explosive gases. In fact it is slotted over most of its length to reduce weight. The wall of cartridge section 38 does not have to be excessively heavy because it is of small diameter compared to the diameter of the mortar tube. Less noise is noted, and this is explained by a muffling elfect between the cartridge section 38 and mortar tube 26.

As the projectile 32 moves relative to the cartridge 40, the pin 58 in groove 60 causes it to spin or rotate. The friction between cartridge 40 and mortar plug 28 prevents the cartridge from rotating. As the projectile separates from the cartridge the gases escape through port 12 thereby reducing the visible muzzle flash. The cartridge then drops by gravity out of port 12. As the round does not have fins, it occupies less volume in transportation and storage.

FIG. 5 illustrates a modified round. The projectile 132 has a cylindrical body 134 of the same diameter as the inside of mortar tube 26. Body 134 is filled with explosive 136. The rear portion 138 of the projectile is reduced in diameter by twice the wall thickness of cartridge 140, and fits snugly in bore 142 of the cartridge. Powder 152 is sealed between Wad 154 and base 144 which contains percussion cap 156. Protuberance 148 on the cartridge mates with any one of increment rings 150 in the projectile. Pin 158 on the cartridge fits in helical groove 160 to spin the projectile. The operation is the same as for the round shown in FIG. 3. It is fired from a mortar similar to that illustrated in FIGS. 1 and 2 except the port 12 must be larger because of the larger cartridge.

It will be apparent that the embodiments shown are only exemplary and that various modifications can be made in construction and arrangement within the scope of the invention as defined in the appended claims.

We claim:

1. A round of ammunition having spin means and adapted to be launched from a guide tube having a port on the underside of said tube, a plug closing said tube at the breech, and a firing pin passing through said plug and extending into said tube; said round comprising in combination: a projectile and a cartridge, said cartridge containing a propellant charge, said cartridge being snugly fitted within said projectile along cylindrical surfaces, said projectile being adapted to be propelled axially away from said cartridge in response to the ignition of said charge, the propulsion of said projectile being due entirely to the action of gas pressures contained within the cavity formed by said cartridge and said projectile, said cartridge being strong enough to withstand said gas pressures, said projectile having a pin on its inner surface which fits in a rifling groove in the surface of said cartridge, said rifling groove having a predetermined helical angle, said cartridge having a percussion igniter positioned so that when said round is dropped into said tube said firing pin actuates said igniter causing said charge to be ignited, said projectile thereupon being propelled axially away from said cartridge, the friction between said cartridge and said plug preventing said cartridge from rotating, said groove thus imparting a rotation to said projectile, the magnitude of said rotation being determined by said predetermined helical angle.

2. The invention in accordance with claim 1, self-contained adjustable range means being. additionally provided, said means comprising: increment means along said cylindrical surfaces for varying the size of the cavity formed by said cartridge and said projectile, the size of said cavity determining the force imparted to said projectile.

3. The invention in accordance with claim 2 wherein said increment means comprises: a protuberance on one of said surfaces and mating rings on the other of said surfaces.

4. An ordnance firing system comprising in combination: a slotted guide tube having a port on its underside, means for adjusting the elevation of said tube, a plug closing said tube at the breech, a firing pin passing through said plug and extending into said tube, and a round of ammunition adapted to be launched from said tube, said round comprising a projectile and a cartridge, said cartridge containing a propellant charge, said cartridge being snugly fitted within said projectile along cylindrical surfaces, said projectile being adapted to be propelled axially away from said cartridge in response to the ignition of said charge, the propulsion of said projectile being due entirely to the action of gas pressures contained within the cavity formed by said cartridge and said projectile, said cartridge being strong enough to withstand said gas pressures, said projectile having a pin on its inner surface which fits in a rifiing groove in the surface of said cartridge, said rifiing groove having a predetermined helical angle, said cartridge having a percussion igniter positioned so that when said round is dropped into said tube, said firing pin actuates said igniter causing said charge to be ignited, said projectile thereupon being propelled axially away from said cartridge the friction between said cartridge and said plug preventing said cartridge from rotating, said groove thus imparting a rotation to said projectile, the magnitude of said rotation being determined by said predetermined helical angle and the direction of said projectile being controlled by said tube, said cartridge dropping from said tube by gravity through said port.

5. The invention in accordance with claim 4, there being additionally provided: increment means along said cylindrical surfaces for varying the size of the cavity formed by said cartridge and said projectile, the size of said cavity determining the force imparted to said projectile.

6. The invention in accordance with claim 5 wherein said increment means comprises: a protuberance on one of said surfaces and mating rings on the other of said surfaces.

References Cited UNITED STATES PATENTS 1,480,957 1/1924 Schneider 89-13 2,378,691 6/1945 Fanger et al. 89-1.3 2,415,803 2/ 1947 Brandt 102-65 .2

741,738 10/1903 Thomas 102-51 1,336,656 4/1920 Rogozea 42-1.2 1,741,900 12/1929 Alden 102-38 2,359,515 10/1944 Fanger 102-49 1,721,704 7/1929 Madaschi 89-13 FOREIGN PATENTS 28,116 9/ 1 924 France.

125,612 5/1919 Great Britain.

308,476 10/ 1920 Germany.

570,257 1/ 1924 France.

120,373 5/ 1901 Germany.

SAMUEL W. ENGLE, Primary Examin r.

U.S. C1. X.R. 102-38, 49.1 

1. A ROUND OF AMMUNITION HAVING SPIN MEANS AND ADAPTED TO BE LAUNCHED FROM A GUIDE TUBE HAVING A PORT ON THE UNDERSIDE OF SAID TUBE, A PLUG CLOSING SAID TUBE AT THE BREECH, AND A FIRING PIN PASSING THROUGH SAID PLUG AND EXTENDING INTO SAID TUBE; SIAD ROUND COMPRISING IN COMBINATION: A PROJECTILE AND A CARTRIDGE, SAID CARTRIDGE CONTAINING A PROPELLANT CHARGE, SAID CARTRIDGE BEING SNUGLY FITTED WITHIN SAID PROJECTILE ALONG CYLINDRICAL SURFACES, SAID PROJECTILE BEING ADAPTED TO BE PROPELLED AXIALLY AWAY FROM SAID CARTRIDGE IN RESPONSE TO THE IGNITION OF SAID CHARGE, THE PROPULSION OF SAID PROJECTILE BEING DUE ENTIRELY TO THE ACTION OF GAS PRESSURES CONTAINED WITHIN THE CAVITY FORMED BY SAID CARTRIDGE AND SAID PROJECTILE, SAID CARTRIDGE BEING STRONG ENOUGH TO WITHSTAND SAID GAS PRESSURES, SAID PRO- 